U.S. Pat. No. 8,561,262 B1 discloses a damping device for a hinge assembly. According to its specification, the damping hinge assembly includes a housing (10), an arm (12), at least one spring (14), a maintaining member (16), a damper (18), and an adjustment member (20). The arm (12) is pivotally connected to the housing (10). The housing (10) includes a chamber (36). The spring (14) is mounted in the chamber (36) of the housing (10) and serves to provide a resilient closing force when the housing (10) is pivoted with respect to the arm (12) and is thereby being closed with respect thereto.
The maintaining member (16) is fixedly mounted in the chamber (36) of the housing (10) and has a path (72) for receiving the damper (18). The damper (18) is mounted in the path (72) of the maintaining member (16) and corresponds to the arm (12). The damper (18) has a piston rod (76). The adjustment member (20) is movably mounted to the maintaining member (16) and has a protruded portion (92) to correspond to the piston rod (76) of the damper (18). When the adjustment member (20) has been displaced with respect to the maintaining member (16) to a first position, the protruded portion (92) of the adjustment member (20) is aligned with the piston rod (76) of the damper (18). Therefore, when the housing (10) is being closed with respect to the arm (12) in this state, the damper (18) is pushed and displaced by the arm (12). As a result, the piston rod (76) of the damper (18) is pressed against the protruded portion (92) of the adjustment member (20) and is thereby retracted to produce a damping effect. If the adjustment member (20) has been displaced with respect to the maintaining member (16) to a second position instead, the protruded portion (92) of the adjustment member (20) will not correspond in position to the piston rod (76) of the damper (18), and if the housing (10) is subsequently closed with respect to the arm (12), the piston rod (76) of the damper (18) will not be pressed against the protruded portion (92) of the adjustment member (20) and hence will not produce any damping effect.
In short, the piston rod (76) of the damping device can produce a damping effect when the adjustment member (20) has been displaced with respect to the maintaining member (16) to the first position, but if the adjustment member (20) has been displaced with respect to the maintaining member (16) to the second position, the piston rod (76) of the damping device cannot be pressed against the protruded portion of the adjustment member to produce the damping effect. In other words, the damping function of the damping device only has an ON state and an OFF state. Lacking a damping function adjusting mechanism, the damping device of the aforesaid US Patent still leaves room for improvement.